Is the Mattress Protector actually waterproof? November 20, 2018 09:16 Updated Follow We've done our research and can confirm they are 100% waterproof - creating the perfect barrier from spills and stains. Related articles How do I use my Simba Mattress Protector? Why should I choose a Simba Mattress Protector? What certifications does the protector have? How long does the Aloe Vera in the Fitted Sheet last? What makes the Simba Fitted Sheet special?